1. Field of the Invention
This invention relates to an annular spacer which, during the vulcanization in a metal mold of an unvulcanized rubber hose having a mandrel pierced therethrough, is used as fitted around the mandrel in intimate contact with either of the opposite ends of the unvulcanized rubber hose.
2. Description of the Prior Art
Heretofore, in the manufacture of a vulcanized reinforced hose (rubber hose incorporating a reinforcing layer) by the use of a metal mold, it has been customary to effect the vulcanization by piercing a mandrel 2 through an unvulcanized hose 1 consisting of an inner rubber layer 1a, a reinforcing layer 1b, and an outer layer 1c, inserting the hose 1 as wrapped on the mandrel 2 in a cavity 3a of a metal mold 3, and subjecting the hose to a treatment for vulcanization. The metal mold 3 has formed each at the opposite ends of the cavity 3a a stepped portion 3b adapted for the mandrel 2 to be accurately supported along the axis of the cavity 3a so as to avoid otherwise possible loss of uniformity of the wall thickness of the hose.
The demand for hoses, however, has a general trend that even hoses of given inside and outside diameters are desired to be available in varying lengths. Consequently, the manufacture of hoses has necessitated use of numerous metal molds of dissimilar lengths.
Generally, the cavity in a metal mold is formed so that the longitudinal extent thereof may be about 1 to 2 mm greater than the length of unvulcanized hose. When the insertion of the unvulcanized hose in the metal mold and the removal of the vulcanized hose from the metal mold are performed by an automatic operation, even a positional deviation of only 3 to 4 mm suffered to occur in the insertion of the unvulcanized hose in the longitudinal central portion of the cavity of the metal mold can deprive the produced hose of its commercial value. For the elimination of such positional deviation, therefore, much time and labor is required in the setting of the equipment for the automatic operation.